Damper control system



Jan. 21, 1936. oss 2,028,249

DAMPER CONTROL SYSTEM- Filed NOV. 10, 1934 I VENTOR.

in? M 22 M5 V9 ATTORNEY.

Patented Jan. 21, 1936 UNITED' STATES PATENT OFFICE Claims.

This invention relates to devices such as damper control systems andmethods.

One object of the invention is to provide a device of the characterdescribed having improved means to eliminate the noise and roar whichoccurs in the stack of a furnace, par- X ticularly of the oil firedtype, and nevertheless to permit easy ignition and efficient normaloperation thereof; and also to increase the conservation of fuel. 1

Because of the frequent difficulty in lighting up an atomizing oilburner in a house heating furnace, the damper is setso as to maintainmaximum draft. This is necessary because the burner flame may pull outor blow off at any normal temperature, and especially while the furnacechamber is cool, leaving the chamber charged with products of combustionwhich prevent for a time the further ignition of the burner. While theflue is cool, the draft exerted thereby is low. But by maintaining themaximum draft possible, the furnace chamber is rather rapidly refilledwith fresh air. Now, after the burner has been finally ignited, theflame proceeds to roar up the chimney. This is so especially while thefurnace chamber is at a relatively low temperature so that the fuelcannot be consumed withinthe furnace chamber, and the resultant longflame extends into the stack. In the case of a steam or hot. waterboiler, the fire box may remain at a relatively low temperature for aconsiderable time: but the roaring often occurs even after the furnacehas been fully heated up. I have found that if the draft issubstantially reduced. this roaring is eliminated, and, of course, animportant saving in fuel results. But because of the need of maximumdraft in li hting the burner, it is inconvenient and troublesome tochange the damper setting. The advantages of the invention becomeespecially clear on considering that the oil burner may be automaticallyignited and cut off, and hence may be intermittent in operation,according to the present practice, to maintain the temperature of thesteam or water substantially constant. It is an object, therefore, ofthis invention to avoid these difficulties which I have perceived.

Another object of the invention is to provide a device having relativelyfew and simple parts and which is inexpensive to manufacture and installand which is durable, reliable andefllcient in use.

Other objects and advantages of the invention will become apparent asthe specification proceeds.

With the aforesaid objects in view, the invention consists in the novelcombinations and arrangements of parts hereinafter described in 5 theirpreferred embodiments, pointed out in the subjoined claims, andillustrated in the an- I nexed drawing, wherein like parts aredesignated by thesame reference characters throughout the several views.

In the drawing:

Figure 1 is a fragmentary view with parts in section taken along ahorizontal broken line l-l of Fig. 2, showing a device embodying theinvention.

Fig. 2 is a side view in elevation thereof.

Fig. 3 is a fragmentary view in elevation taken at the opposite side ofthe device.

Fig. 4 isa diagrammatic view in elevation showing a modified deviceembodying the inven- .0 tion.

The advantages of the invention as here outlined are best realized whenall of its features and instrumentalities are combined in one and thesame structure, but, useful devices may be 25 produced embodying lessthan the whole.

It will be obvious to those skilled in the art to which the inventionappertains, that the same may be incorporated in several differentconstructions. The accompanying drawing, 30

therefore, is submitted merely as showing the preferred exemplificationof the invention.

Generally described, this invention provides means responsive totemperature in a firing chamber, or in a passage for the products of 35combustion, or adjacent thereto, as to be affected by a temperaturethereof along a suitable point adjacent to or in the path of travel ofsuch gases. In other words, the temperature sensitive means isresponsive to such temper- 40 ature as distinguished from that of thesteam, hot water or the like, heated by the furnace. Hence thetemperature sensitive means, while directly or indirectly affected bythe temperatu .re mentioned, is quickly responsive to oper- 5 ate adraft control means for the purposes stated herein. Two results follow:it is unnecessary for sufficient time to elapse to permit the water orsteam to be heated, and even if the water or steam remain at acomparatively 50 uniform temperature, the invention is independentlyoperative to control the draft as where the burner works intermittently.The chamber may be fired by gas or oil.

' Referring in. detail to the drawing, l0 denotes 66 under control ofthe element l1.

a'device embodying the invention, of which ll may indicate any furnace,such as a hot water or steam boiler having a firing box or chamber, withwhich the flue or duct I2 is in communication to discharge the gaseousproducts of combustion into a stack. Desirably the boiler II is fired byan atomizing oil burner and the burning of the fuel is controlled inpart by the draft through the fire box. I

The duct 12 may have a side inlet 13, in which may be set an annularframe I4 of angular cross section, for pivotally mounting a damper IS onpins l6 lying along a horizontal line above the center of the damper,and the pins being journaled in the frame.

Extending through the duct or stack portion 12 is a thermosensitivemetallic rod ll of suitable composition. For easy mounting said rod mayextend through the wall of the duct as at l3 and I3. For fixing one endof the rod or element IT, a split strap 20 may encircle the duct, saidstrap being secured as by bolts 2|, 22 extending through correspondingpairs of ears 23, 24 of the strap. The ears 24 may have laterallyextending portions 25 bolted together at 28, and having mating concavedportions 21 intermediate of the bolts 22, 26 to strongly ad- Justablyengage around the adjacent end 28 of the element [1.

The element I1 is slidably movable through the hole I 9 and is adaptedto actuate means 29 engaged with the damper l5. For example, a bracketstructure 30 may be secured to the frame l4, and having alined ears- 3|,32 to receive therebetween a lever. 33, pivoted on an upright bolt 34passing through the ears. This pivot 34 is as close as possible to thelongitudinal axis of the element 11. The adjacent end of the lever isprovided with an adjustable set screw 35 having a rounded end bearingagainst a corresponding rounded end 36 of the element l1 alinedtherewith. The opposite end of the lever has an angular arm 31 extendinginward into abutment relation with the damper l5 for contacting the sameat a point in close proximity to the axis of the pivots l6, slightlybelow said axis. In this manner the lower portion of the damper isadapted to be inwardly swung To prevent undue downward strain on thelever 33 by the weight of the damper in the inward swung positionthereof, the ear 32 may have a laterally extending plate or T-bar '38 toafford a support for the lever along the path of movement thereof. Sincethe damper I5 is in the nature of a thin plate fly valve, its weight isinsufficient to cause any material friction between the lever and itssupport 38.

The operation of the device In and the method contemplatedby theinvention will now be described. The furnace ll and flue [2 being cold,the element I1 is in contracted condition, and the damper l5 is closed.As this damper is of the atmospheric type, the result is that no air cannow enter the flue except through the furnace chamber so that themaximum draft available is obtained. Now the oil burner is ignited, andthe draft helps the ignitionto occur by preventing choking of the flame.Should the flame accidentally blow out, the products of combustion arerapidly withdrawn by the draft from the firing chamber, so that theburner can again be ignited. During all this time, the element 11 beingremote from the fire box has not been affected by any puff of flame. sothat the damper remains set, and the burner can be again ignited. Assoon as ignition has been fairly completed, and the burner is inoperation, the hot products of combustion passing up the stack rapidlyheat up the element ll. Suflicient heating of the element may beeffected within one. minute or even less, and it may be sufllcient forthe element to attain a temperature of as little as several hundreddegrees in order to operate. Then when the element I1 expands, it movesthe set screw 35 to cause the lever 33 to swing clockwise to move thedamper l5 inward about its pivots I6. Air now enters the flue throughthe inlet I3 and reduces the draft in the furnace chamber. The noise androar of the flames in the flue are thus almost immediately ended. As theflue heats up, the damper l5 opens a little further, but not much more,and the pull of the stack becomes greater so that combustion can proceedat the desired,

rate. But for the same reason the flow through the inlet l3 becomesgreater so that an equilibrium is reached at which combustion iseffected with a minimum supply of air, resulting in conservation offuel.

Thus the method requires that after the fuel is ignited, the temperatureat the stack is observed, since the element [1- may be regarded as a.temperature indicator, and the damper set to reduce the draftaccordingly. The stack temperature will show that the combustion of thefuel hasbeen regularly begun.

If the burner is intermittently operated to keep a uniform housetemperature, the air passing through the furnace and flue will cool offthe element l1, and even the sheet metal duct 12, and as the dampercloses the cooling increases, so that the burner is ready to be againignited, the device is back again substantially in the initial positionhereinbefore described. Nevertheless because the damper closes slowly,the furnace walls will not cool ofl as rapidly as where the damper wasfully closed, according to the previous practice. Hence damage to thefurnace may be avoided.

If in igniting the burner, a puff or explosive ignition occurs, thedamper I 5 may be held closed by the support 38 acting as a stop toprevent flame from blowing out from the flue.

The projecting parts of the element l1 and its associated parts may beregarded as aircooled means facilitating the cooling of the ele: ment byair outside of the flue.

temperature than hereinbefore mentioned, as may be desired.

In Fig. 4 is shown a modification of the invention including a steamboiler having an atomizing oil burner 4| firing into the chamber 42 ofthe boiler, and the spent gases passing out through the flue 43. Adamper 44 may be located in the latter, and a damper 45 may be disposedto supply air to the base of the firing chamber 42. A temperaturesensitive element 46 may be disposed in or adjoining passages controlledby one or both of the dampers, or in a passage 41 that contains baffles48. "The dampers may be moved from the dot-dash line positions to thedotted line positions to reduce the draft, by any suitable operatingmeans 49 connected at 50, 5| with the means 46 for actuation by thelatter. A remote temperature indicator 52 may be connected at 53 to themeans 46, independently of 49, and a remote control 54 may be connectedat 55 to the operating de- The element f may be made to operate thedamper at a higher' vice such as 49 so that the operator may set thedamper after observing the temperature, according to my improved method,in the event that it be desired to operate the device man ually insteadof automatically.

Where the burner 4| is intermittently operated, the fuel line 56therefor may be controlled by a suitable means'5l that is actuated byany device 58 responsive to steam pressure or to room temperature as maybe preferred.

It will be appreciated that various changes and modifications may bemade in the device as shown in the drawing, and that the same issubmitted in an illustrative and not in a limiting sense, the scope ofthe invention being defined in the following claims.

I claim:

1. In a device having a furnace, a stack therefor having an opening incommunication with the atmosphere, and a damper for said opening movablebetween open and closed positions and adapted, in the closed position,to cause the stack to exert a maximum draft in the furnace for the rapidstarting of a fire therein, the combination with said stack and damper,of metallic means expansibly responsive to the temperature in the stack,and actuator means controlled by the temperature responsive means tomove the damper from the closed position to an open position thereof,and the actuator means having means to cause a rapid initial openingmovement of the damper for an initial relatively low rise in temperaturefrom cold in the stack, and a subsequent opening movement of the damperat a decreased rate for a further rise in temperature in the stack,whereby the maximum draft is rapidly reduced as combustion is initiated,and the draft regulated as the temperature in the stack continues torise.

2. In an oil furnace, the combination with a stack and an atmosphericdamper therefor movable from closed to open position to reduce the draftin the furnace, with the stack havingsuflicient capacity to exert anexcessive draft in the furnace in the closed position of the damper tofacilitate ignition of the oil, of means responsive to temperature inthe stack, and actuator means for the damper controlled by thetemperature responsive means, said damper being moved from closedposition to an open position upon a relatively low rise in temperaturein the stack to cause a substantial reduction in draft substantially assoon as combustion in the furnace is begun, to obtain a normal draft,and the actuator means causing said damper to gradually regulate thedraft as the stack temperature increases to maintain normal conditionsof combustion in the furnace.

3. In a furnace, the combination with a stack therefor, having a flowcontrolling open tube directly communicable with the atmosphere, and adamper within said tube movable from closed to open positions toregulate inflow of air into the stack for reducing the draft, saiddamper being swingable about an axis in relative proximity to the centerof the damper, of means responsive to the temperature in the stack, andactuator means controlled by the temperature responsive means, saidactuator means having substantially continuous engagement with thedamper in close proximity to the axis thereof so as to swing said damperat a decreasing angular rate to cause a marked initial reduction indraft upon initiation of combustion and then a gradual regulatorydecrease in draft as the stack temperature increases upon attainingnormal combustion conditions.

4. In a furnace, the combination with a stack therefor having anopening, and a damper for said opening mounted for swinging movementabout an axis in proximity to the centerof the damper, the damper beingmovable from closed to open position to decrease the draft in thefurnace, of means responsive to the stack temperature, and actuatormeans controlled thereby to operate the damper, said temperatureresponsive means and said actuator means being mova ble substantiallyalong a plane, said actuator means engaging the damper in closeproximity to the axis thereof to swing the damper from full closed toopen positions at increasing rates of speed with respect to thetemperature increases in the stack, as and for the purpose set forth.

5. In a furnace, the combination with a stack therefor having a flowcontrolling open tube directly communicable with the atmosphere, and adamper within said tube movable from closed to open positions toregulate inflow of air into the stack for reducing the draft, saiddamper being swingable about an axis in relative proximity to the centerof the damper, of means responsive to the temperature in the stack, andincluding a metallic element extending through the stack, separate meansencircling the stack and engaging one end portion of the element to fixsaid end portion thereof, the stack having a hole for guiding the otherend portion of the element, a lever actuable by said element, means formounting said lever on said tube, and said lever having engagement withthe damper in close proximity to the said axis thereof, as and for thepurpose set forth.

6. In a furnace, the combination with a stack for the furnace having anopening communicable with the atmosphere, and a damper in said openingswingable about a horizontal axis in proximity to the center of thedamper so that the damper is movable from closed to open positions toreduce the draft in the furnace of a transverse substantially horizontalrod extending substantially through the stack so as to expand andcontract subject to the temperature in the stack, said rod being fixedat one end and being movable at its other end through a hole in the wallof the stack, a lever mounted on the stack and having a substantiallyvertical axis, said lever being actuable by the movable end of said rod,the damper having its axis of swinging movement above the center ofgravity of the damper so that the latter normally depends in uprightclosed position, said lever having abutment with the dampersubstantially at a diameter thereof, below the axis of swinging motion,to swing the damper from closedto an open position to substantiallyreduce the draft in the furnace upon expansion of the rod in response toa relatively small rise in stack temperature when combustion in thefurnace is begun and then to slowly reduce the draft in the furnace ascombustion progresses and the stack temperature diminishes.

7. In a furnace, the combination with a stack therefor having an openingdirectly communicable with the atmosphere, and a damper for initiallyclosing said opening, of means for controlling said damper, said meansincluding an element responsive to stack temperature, said damper beingmounted for swinging movement about an axis spaced from the center ofthe damper, said means including an inwardly movable portion controlledby said element and engaging the damper on the outside of the stacksubstantially at a central region of the damper spaced from the swingingaxis thereof so'that abackfire in the furnace is unable to swing thedamper open.

8. In a furnace, the combination with a stack therefor having an openingcommunicable with the atmosphere, and a damper for said opening, ofmeans for controlling said damper, said means including a temperaturesensitive element responsive to a rise in temperature upon initiation ofcombustion in the furnace, said damper being swingable about asubstantially horizontal axis above the center of gravity of the damperso that the damper lies in normally upright closed position, and saidmeans having a portion movable substantially horizontally under controlof said element, said portion having external lost motion abutmentagainst the damper below the said axis and in relatively close proximitythereto to open the damper at a rapidly decreasing rate, and for thepurpose set forth.

9. In a furnace, the combination with a stack therefor having an openingdirectly communicable with the atmosphere for controlling draft in thefurnace, and a damper for said opening movable from closed to openpositions to reduce the draft, of a substantially straight rod extend--ing through the stack and exposed for direct contact with the gasestherein so as to expand and contract according to temperature changes inthe stack, and actuator means controlled by said rod, said damper beingswingably mounted, and said acutator means having lost motion camengagement with the damper in close proximity to but in spaced relationfrom the axis of swinging motion of the damper to open the damper at adecreasing rate of speed for equal temperature increments in the stack.

10. In a furnace, the combination with a stack therefor having anopening communicable with the atmosphere to vary the draft in thefurnace, and. a swingable damper for said opening movable from closed toopen position, to reduce said draft, of means responsive to thetemperature in the stack, and actuator means controlled thereby, saidactuator means having a portion movable substantially along a plane andabutting said damper in relatively close proximity to the axis ofswinging motion thereof for a lost motion camming engagement, as setforth.

GEORGE H. R638

